In the prior art, piston reversing control valves for this style of downhole hydraulically powered pump are simple in nature in that they function to reverse the piston assembly when it reaches the end of a stroke without regard to the well fluid pressure and the presence of a two-phased, gas and liquid, medium within the pumped zone of the well. The primary disadvantage of the prior art reversing control valves is their inability to compensate for a two-phased medium cavitation or a dry hole condition in the well and the well pressures. The result of this inability in the prior art is damage to the pump which is caused by the pump being operated without the proper fluids and pressures being present which causes the piston to greatly accelerate during the stroke and then contact a liquid at some position of the stroke thereby damaging components of the pump.